The investigation of two sequential steps in the bacterial biosynthesis of cobalamin (Vitamin B12) will be conducted by Dr. Ford. Direct assay of extracts of Clostridium tetanomorphum for activity involved in cobalamin biosynthetic activity will be performed. Crude extracts showing biosynthetic activity will be subjected to enzyme purification procedures. Dr. Wu-Yuan will study the glucan-induced cellular agglutination of Streptococcus mutans and its role in dental plaque and dental caries formation. An agglutination-deficient mutant of S. Mutants B13 will be employed and its physiological, morphological, and cariogenic properties will be exmained and compared with the wild type parent cells. Dr. Sampsell will investigate the effect of environmental temperature and alcohol on survival and alcohol dehydrogenase activity in Drosophila with enzymes of varying thermostability. Alcohol tolerance will be studied following heat treatments. Developmental profiles of enzyme activity will be completed for flies raised under various conditions. An autoradiographic light microscopic analysis of selected central nervous system structures will be conducted to determine the effect of lead-exposure on neuron genesis and survival. Trace metal concentrations of selected tissue will be measured in order to determine whether a lead-induced trace metal deficiency can be produced in pups on diet suboptimal in trace metals (Cu, Mn). Selected enzyme activity will be measured (Dr. Austin, Hollins, and Mylroie). A kinetic fluorometer is being constructed by Dr. Sherman to measure changes in ultraviolet fluorescence emission from bacteriohodopsin following excitation by visible light. Changes in fluorescence linked temporally to photocycle intermediates will be analyzed for indication of opsin conformational change.